Diffusional mass transfer (Ostwald ripening) between emulsion droplets has been studied. By using sedimentation field-flow fractionation (SdFFF) coupled with gas chromatography, the disperse phase composition can be obtained for monosized droplet fractions. Two liquids, A and B, were mixed together and then emulsified. The mass transfer between droplets of different size was driven by differences in capillary pressure, such that the small particles were enriched in the less soluble B component. At low concentrations of B, a bimodal size distribution emerged, with the small particle size fraction strongly enriched in B. There is a strong agreement between the experimental data and current theories for two-component disperse phase emulsions as developed by Kabalnov et al.